<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .menu {
          position: relative;
        }
        .menu-title {
          display: flex;
          align-items: center;
          justify-content: center;
          width: 100px;
          height: 30px;
          border: 1px solid #333;
          padding-right: 20px;
          background: url(images/down.png) no-repeat 90px 6px;
          background-size: 24px;
        }
        /* 默认隐藏下拉菜单内容*/
        .menu-content {
          height: 200px;
          width: 200px;
          background-color: pink;
          padding-top: 4px;
          position: absolute;
          left: 0;
          top: 100%;
          z-index: 9999;
          display: none;
        }
        /*鼠标滑上去，显示下拉菜单内容*/
        .menu:hover .menu-content {
          display: block;
        }
      </style>
</head>
<body>
    <div class="menu">
        <div class="menu-title">产品分类</div>
        <!-- 下拉菜单内容 -->
        <div class="menu-content">.......</div>
      </div>
</body>
</html>